The present invention relates to complementary circuits and structures, and more particularly, to such circuits and structures that provide reversible currents, such as for motor control.
Many applications, such as power seats, power windows, power door locks, retractable headlights, etc., in an automobile, require the application of a reversible current to a load, such as a DC motor, wherein the direction of current flow is controlled by low level logic signals. This can be done by a complementary pair of field effect transistors (FETs) or a pair of NPN and PNP bipolar transistors. FETs are especially desirable due to their low drive current requirements. More particularly, in order to obtain a low source to drain voltage drop, while controlling a large, e.g., at least one ampere, load current, vertical FETs are required, wherein the drain output terminal is the substrate. However, the complementary configuration typically requires separate substrates in separate packages or hybrid construction since the drains are of opposite conductivity type. This increases packaging and testing costs and reduces reliability due to the required interconnections.
It is, therefore, desirable to have a complementary vertical FET circuit and structure that can be fabricated on a common substrate.